There’s not a lot to talk about in terms of holiday customs, because the Islamic New Year is usually marked quietly, perhaps with some prayer and reflection on Muhammad’s flight from Mecca to Medina, the هِجرة (hijrah), which is the event that marks the year 1 in the Islamic calendar. The next ten days, the first ten of the year, are not particularly celebratory, especially for the شيعة (shīʿah) community, which commemorates the anniversary of the events leading up to the martyrdom of إمام حُسين (Imām Ḥusayn, ʿAlī’s son and the third Imam) on the tenth, the day known as عاشوراء‎ (ʿĀshūrāʾ).

As was the case at the Gregorian New Year, “new year” is is رأس السَنة (raʾs al-sanah) or رأس العام (raʾs al-ʿām). To specify that you are talking about the Islamic New Year, you might want to say رأس السَنة الهِجرية (raʾs al-sanah al-hijrīyah) or رأس العام الهِجري (raʾs al-ʿām al-hijrī), هِجري being the name of the Islamic lunar calendar whose year 1 is commemorated by the Hijrah. That kind of specification is only important on the occasions when the Islamic and Gregorian New Years fall around the same time; most of the time the Hijri lunar calendar is out of phase with our solar calendar and it’s pretty obvious which New Year you’re talking about.

If “raʾs al-sanah” sounds familiar to you, maybe that’s because it sounds so much like the name of the Jewish New Year, “Rosh Hashanah,” and that’s about right, since Hebrew and Arabic are branches of the same Semitic root language.